PORTLAND, Maine - Ronald Lee Herrick, who donated a kidney to his dying twin brother 56 years ago in what's recognized as the world's first successful organ transplant, has died of complications following heart surgery. He was 79.

Herrick died Monday at the Augusta Rehabilitation Center in Augusta, said his wife, Cynthia. He had been in deteriorating health since his October surgery, she said.

Herrick gave a kidney to his twin brother, Richard, at what is now Brigham and Women's Hospital in Boston. The 5 1/2-hour operation on Dec. 23, 1954, kept Herrick's brother alive for eight years and was the first successful organ transplant, according to the United Network for Organ Sharing. Lead surgeon Dr. Joseph Murray went on to win a Nobel Prize.

The operation proved that transplants were possible and led to thousands of other successful kidney transplants and ultimately the transplant of other organs. Doctors had tried a handful of transplants worldwide without success up to that point, said Murray, who went on to perform another 18 transplants between identical twins.

"This operation rejuvenated the whole field of transplantation," Murray, 91, told the Associated Press in a phone interview from his home in Wellesley, Mass. "There were other people studying transplants in four or five different countries, but the fact that it worked so well with the identical twins was a tremendous stimulus."

Herrick was raised on a family farm in Rutland, Mass., where he graduated high school. He later served in the army.

At 23, Herrick was glad to give up a kidney if it would help his brother, who was dying from chronic nephritis, an inflammation of the kidneys. Murray thought the odds of a transplanted organ being accepted would be enhanced since they were identical twins.

Before the operation, many people opposed the idea of transplanting a body organ, equating it with desecration of a body. Others felt it was unethical to operate on healthy humans, and respected editors of medical journals wrote that it was contrary to the Hippocratic Oath's vow to never do harm to anyone, Murray said.

But Herrick never wavered and the operation went on as planned with no complications. Richard Herrick met his future wife, Clare, in the recovery room, where she was a nursing supervisor.

"He was the only one in the world who could save his brother's life, so he was going to do it," said Cynthia Herrick. "There was no question about it."

Ronald and Cynthia married in 1959, and they moved to Maine in 1968.

He taught math for 37 years, in both Massachusetts and Maine. He also raised cows and cut hay for decades on a small farm he bought in Mount Vernon.

In 1997, he and his wife sold their farm and moved to a house in Belgrade.

Herrick rarely mentioned the operation to people he knew, but he was known in the medical world for his pioneering role.

He and Murray marked the 50th anniversary of the operation at the National Kidney Foundation's 2004 U.S. Transplant Games in Minnesota, said foundation spokeswoman Ellie Schlam.

Herrick and Murray together lit the flame to kick off the games, an Olympic-style event for athletes who have received organ transplants.

"He was a humble man. You got the sense he didn't think he'd done anything extraordinary, but that he had done what a brother would do," Schlam said. "He wasn't too impressed with himself, but he was impressive."